An Ecological Model to Classify and Monitor Mountain Plover Nesting Habitat on Grasslands in Colorado
A multivariate statistical model based on vegetation and soil surface characteristics was developed to classify and monitor mountain plover (Charadrius montanus ) habitat groupings and nest selection. Data were collected on the shortgrass prairie, Pawnee National Grassland, Colorado. Vegetation and soil surface characteristics were sampled from late April to early June of 1999 and 2000 during the nesting season. Samples were collected on random sites in 43 sections and at 54 nest sites within adjacent townships. Random data were clustered into three habitat groups consisting of high, mid and low nesting habitat. Key variables in the model for classifying and monitoring nest habitat were percent bare ground, percent canopy cover for blue grama (Bouteloua gracilis ) and buffalograss (Bouteloua dactyloides ). The three nest habitat groupings were quantitatively identified with an estimated 97 percent accuracy. The model classified the 54 mountain plover nest sites as either high, mid or low nesting habitat. High mountain plover nest preference (39 nests) for bare ground was 46 percent, with blue grammar 27 percent and buffalograss at 2 percent (n = 39 nest sites). Mid classified nests (12) selected 23 percent bare ground, 60 percent blue grama and 1 percent buffalograss. Three nests were classified as low nesting habitat, which exhibited 25 percent bare ground, 41 percent buffalograss and 17 percent blue grama. Mountain plovers selected nest sites that had short plant structure, a mean visual obstruction reading (VOR) of 0.25 cm at nesting and ranged from 0 to 1.6 cm. Nest selection was similar for VOR among the three groups (P >0.10). Plant structure (VOR) from 499 random sites was grouped into three categories; tall, intermediate and short and ranged from 0.6 to 11.4 cm. Short VOR plant structure of 2.2 cm or less (<1-inch) is potential nesting habitat and may be achieved by fall or winter grazing within high plover nesting habitat. This multivariate model along with visual obstruction groupings for classifying and monitoring mountain plover habitat on the shortgrass prairie are simple to use, reliable, repeatable and cost effective to meet management objectives and monitoring plans.